Microsoft's Expression product line seems very impressive. When you take into consideration the cross-platform (WPF/E) power and the extreme flexibility of WPF/XAML, and not to mention the solid power of programmability (something Flash lacks in boatloads) WPF/E will most probably revamp the Internet itself!
If you don't know anything about all this, think power of the world's best programming language, mixed with futuristic Final Fantasy like software interfaces. The future is finally here. Where do I want to go today? I wanna go to the place where they store the bits of Sparkle in Microsoft!
If you've worked in Flash and if you've worked in .NET, you just KNOW that the possibilities are mind-boggling. I have half a mind to create a time machine and go to the release date!!
WPF/E supports portable devices, Mac OS X, and possibly Linux as well! This is one of those few (if not the only one) things Microsoft made that is cross-browser compatible to such extremes. Check out Sparkle's features.
Windows Vista will finally be that massive graphical step in a visually better computing world. Not to mention all the other stuff - but I'm a graphic guy so I don't see nothin' else! :-P
Also, check out the ATLAS page. I'm gonna get my hands dirty with all this this weekend! 
I'm still shaking from excitement over Expression. I better stop trying to write my thoughts about it before I go completely nuts!
EXPRESSION ROCKS!!!